Effect of exogenous interferon-gamma (IFN-gamma) on peripheral blood immune markers as part of a phase I clinical trial of combined IFN-gamma with nivolumab (Nivo) in patients (pts) with select solid tumors.

97Background: IFN-gamma is a known activator of PD-L1 expression and plays a key role in immune activation. We present initial correlative peripheral blood findings after the first 2 cohorts of pts enrolled in a phase I trial of combined IFN-gamma/Nivo in pts with various solid tumors. Methods: Pts with advanced solid tumors who had progressed after at least 1 prior therapy were recruited. An induction phase of IFN-gamma (50 or 75 mcg/m2 subq every other day for 1 week) preceded the combination of Nivo (3 mg/kg IV every 2 weeks) with continuation of IFN-gamma at same dose and schedule for 3 months. Pts with clinical benefit could remain on Nivo alone for up to 1 year. Peripheral blood was analyzed via flow cytometry at baseline, after IFN-gamma induction (prior to Nivo start), and after 6 weeks of combo treatment. Results: 13 pts have been accrued. Pre and post induction samples were collected on all pts. Nine pts had available on-treatment samples at time of data analysis. Comparing blood collections fro...